| 摘要 |
Disclosed is a hydraulic circuit for a construction machine for controlling operation oil that joins an arm cylinder from a boom cylinder-side hydraulic pump during a composite operation resulting from arm-in and boom-up driving. The present invention provides a hydraulic circuit for a construction machine, characterized by comprising: an arm cylinder driven by operation oil from a first hydraulic pump; an arm control valve installed in a channel between the first hydraulic pump and the arm cylinder so as to control the flow of operation oil supplied to the arm cylinder during switching resulting from manipulation of an arm manipulation lever; a boom cylinder driven by operation oil from a second hydraulic pump; a boom control valve installed in a channel between the second hydraulic pump and the boom cylinder so as to control the flow of operation oil supplied to the boom cylinder during switching resulting from manipulation of a boom manipulation lever; an arm-joining control valve installed in a channel between the boom control valve and the arm cylinder such that a part of operation oil from the second hydraulic pump joins the arm cylinder during switching for conducting a composite operation by boom-up and arm-in driving; and a pilot pressure control valve installed in a pilot channel, which applies a pilot pressure in order to switch the arm-joining control valve, so as to block the pilot pressure applied to the arm-joining control valve during switching by the pilot pressure applied to the boom control valve for the purpose of boom-up driving. |
